Husband accusing me of adultery & forcing for divorce what should i do

I am a hindu woman. My husband is accusing me of having an extra marital affair as he read few of msgs over facebook and whatsapp with an online friend of mine. He is mentally torturing me and made me sign an agreement which says that i accept to have cheated. he doesnot work at all and i am small govt employee. his family members are also forcing me to get that agreement registered. I submitted an application in the nearest police station stating all this and that i am living under threat. we have a 10 year old son. I donot want divorce especially for no fault of mine.